Video Transcript
Which of the following better represents a particle model of how electromagnetic radiation propagates?
We can see that in both of these answer options, (A) and (B), the electromagnetic radiation is moving from left to right. We can imagine that both of the red arrows shown represent a ray of electromagnetic radiation. Notice that in answer choice (A), the particles that make up this radiation are spread out compared to that red arrow. In fact, it looks roughly like these particles are arranged in a wave shape.
Imagine though that this ray of light were being shined onto some surface. We would expect light to be incident on the surface at the location of the red arrow, but we wouldn’t expect light to be incident at all these other places. This is because indeed we’re working within the particle model of electromagnetic radiation. In this model, this radiation behaves as a particle and not as a wave.
Answer choice (B) is a better depiction of the particle model of electromagnetic radiation. In this option, we see all of the particles of light, we could call them, incident on our surface at this location. This is what we would expect if we had a ray of light or, say, a laser beam at one particular spot on a surface. For our answer then, we choose choice (B). This option better represents a particle model of how electromagnetic radiation propagates.
